On the Performance of Single Side-Band OFDM for Band-Limited Visible Light Communication

The use of a multicarrier modulation scheme based on orthogonal frequency division multiplexing (OFDM) is a very promising approach to enable high-speed transmissions for band-limited visible light communication (VLC) systems. The existing variants of optical OFDM have been designed mostly to establish a compromise between spectral and power efficiencies, with the premise that the signal is purely transmitted in the baseband, thereby it needs to be real-valued. A common way to synthesize a real waveform with the digital implementation of OFDM is to use Hermitian symmetry. An alternative, but not fully explored, solution without imposing Hermitian symmetry is to upconvert the complex baseband OFDM signal within the limited bandwidth of VLC systems using an appropriate carrier frequency. In this paper, the bandpass transmission of OFDM signals based on optical single side-band OFDM (SSB-OFDM) is considered. The detailed mechanism for the generation and detection of an SSB-OFDM signal with discrete-time processing is presented. To address the bandwidth constraint, spectrum shaping of the SSB-OFDM signal is discussed. Furthermore, performance analyses of spectral efficiency (SE) and bit error ratio (BER) are carried out and the results are verified using Monte-Carlo simulations. Novel insights are provided, highlighting the signal-to-noise ratio (SNR) gain of SSB-OFDM over a baseline direct current-biased optical OFDM (DCO-OFDM) system.